Composite propellant compositions require good mechanical properties, good stability during storage, and controlled burning rates as required for their performance parameters. Since a high percentage of a composite propellant composition of interceptor motors is comprised of ammonium perchlorate oxidizer and a fuel component which is generally aluminum metal bound within rubbery binders, the opportunity of chemical interactions which may occur between the oxidizing functional groups and the fuel component is always present. The presence of other reactive materials contribute further to other chemical interactions. These interactions are desirable during the combustion process; however, the interactions during storage could cause undesirable stability problems.
Thus, a desirable combination would be a change which increases the propellant's burning rate, extends the storage life of interceptor motors, and improves the propellant mechanical properties. The opportunity of acceptance of a triple benefit such as noted is seldom available; however, as further disclosed hereinbelow a triple benefit is derived from the disclosed invention.
From the observation of high-speed photographs of burning solid propellants it has been determined that the combustion of aluminum metal powder occurs at a considerable distance from the propellant's surface. If this combustion or rapid oxidation process were to occur at the propellant's surface, considerably more heat would be transmitted back into the propellant, and a major enhancement of the burning rate would take place. This achievement would result in a reduced need for burning rate enhancers or the complete elimination of their need in the propellant composition.
An object of this invention is to provide aluminum-encapsulated ammonium perchlorate to effect an increase in the burning rate of the propellant composition containing the encapsulated ammonium perchlorate.
A further object of this invention is to provide aluminum-encapsulated ammonium perchlorate to effect an increase in the storage life of interceptor motors containing the encapsulated ammonium perchlorate.
Still a further object of this invention is to provide aluminum-encapsulated ammonium perchlorate to effect an improvement in the propellant mechanical properties containing the encapsulated ammonium perchlorate.